1. Field of the Invention
This invention relates to a catheter for the repair of injured blood vessels. More particularly, it relates to a catheter for the repair of injured blood vessels, which is used for repairing flappy intravascular membrane separated as by excessive expansion of blood vessels, for example, either during disintegration of atheroma which is one cause for intravascular thrombosis or during the course of angioplasty.
2. Description of the Prior Art
Percutaneous transluminal angioplasty (PTA) or percutaneous transluminal coronary angioplasty (PTCA) using a dilating catheter is used as an angioplastic means for dilating or opening the stenosed or occluded part of a tract such as a blood vessel, when stenosis or occlusion occurs. The flow of body fluid on the peripheral side of the tract is thereby improved. This angioplasty is effected, for example by first percutaneously securing the affected portion of the blood vessel in place, passing a guide wire into the blood vessel, inserting a catheter provided at the leading end thereof with a dilating member (balloon) along the guide wire until the dilating member is accurately located at the affected portion involving stenosis or occlusion, subsequently injecting a liquid (such as, for example, a contrast medium or physiological saline solution) under pressure (on the order of several to ten atmospheres) into the dilating member via a hub, and inflating the dilating member in the direction of the inner wall of the blood vessel thereby dilating or opening the stenosed or occluded part of the blood vessel.
The angioplasty of the operating principle mentioned above, however, necessitates highly delicate regulation of the operation involved. If the force exerted by the dilating member to spread the inner wall of the blood vessel radially is too small, the portion of stenosis cannot be sufficiently spread open and becomes liable to reocclusion. Conversely, if the force exerted by the dilating member to spread the inner wall of the blood vessel radially is unduly increased in an effort to spread the portion of stenosis outwardly to a sufficient extent, the intima sustains injury. The dissection and the intima which is so separated assumes the shape of a flap which is exposed to the blood. As a possible result, the dissected membrane will cause coagulation of blood and induce occlusion of the blood vessel. Further, the disintegration of the atheroma which is one cause for the acute myocardial infarction (AMI) develops with advance of arteriosclerosis and, as the result, the intima is similarly dissected in a flap and exposed in situ to the blood in motion to induce thrombus abruptly. If the flow of blood through the blood vessel is resumed as by the therapy of thrombolysis (PTCR) immediately after the onset of the symptoms, the progmosis of the disease is highly pessimistic. Equally in the case of the PTCR, the recurrence of thrombus is controlled as by the infusion of a large amount of urokinase. This measure, however, has a very strong possibility that the intimal flap will induce reocclusion in situ. Once the dessection of the intimal flap described above induces re-occlusion of the blood vessel, there ensures a very serious problem that the case will inevitably necessitate a surgical treatment and the patient will suffer from an enormous burden.
This invention, therefore, has an object of providing a novel catheter to be used for the repair of an injured blood vessel.
Another object of this invention is to provide a catheter for the repair of an injured blood vessel, which is used for repairing the intimal dissected flap because of excessive expansion of the blood vessel possibly entailed during the course of an angioplasty.
Still another object of this invention is to provide a catheter for the repair of an injured blood vessel, which is capable of enabling the intimal dissected flap to be attached securely to the inner wall of the blood vessel by making effective use of the reaction system for blood coagulation.
A further object of the present invention is to provide a catheter for the repair of an injured blood vessel, which is capable of precluding the possibility of re-occlusion of the blood vessel due to the dissection of the intimal flap which is liable to occur as a complication originating in an angioplasty.